i8o PRACTICAL ORGANIC CHEMISTRY and the alkaline reddish-brown liquid (potassium phenate and excess of alkali) acidified with concentrated hydrochloric acicl in the cold. Phenol separates out as a light yellow oil, which is extracted three times with ether. The ethereal solution de- hydrated over anhydrous sodium sulphate is distilled, first on the water-bath until the ether is removed, and then over the flame. The portion boiling at 175 — 185° is nearly pure phenol. It distils as a colourless liquid and solidifies at once on cooling. Yield, 6—7 grams. C0H6OK+ HC1 = CGH5OH + KC1. Properties. — Colourless needles, with a characteristic smell ; m. p. 42—43° ; b. p. 182° ; easily soluble in alcohol and ether ; and in about 15 parts of water at the ordinary temperature ; produces blisters on the skin. Reactions. — i. Make a solution of phenol in water, and to one portion add a drop of ferric chloride. A violet colouration is produced. 2. Add to another portion a drop of bromine water. A white crystalline precipitate of tribromophenol is formed. 3. To a third portion add an equal volume of dilute ammonia and a few drops of sodium hypochlorite and warm gently. A copper-sulphate-blue colour is produced. 4. Add a small fragment of solid sodium nitrite to 5 c.c. concen- trated sulphuric acid and warm very gently until dissolved. On adding about 0*5 gram of phenol, a brown solution is obtained, which rapidly changes to deep blue. If the blue solution is poured into water, a cherry red colouration is produced, which changes to blue on the addition of an alkali (LiebeVmann's 'nitroso J reaction, see p. 159). 5. Mix I gram of phenol with i c.c. of dimethyl sulphate l and add 4 c.c. of a 10 per cent, solution of caustic soda. Warm and shake. The odour of phenol is replaced by that of anisole, which can be extracted from the liquid hy ether (Ullmann's reaction). See Appendix, p. 294. 1 The vapour of dimethyl sulphate is very poisonous, and care should be taken not to breathe it.